Old Frisian was a West Germanic language spoken between the 8th and 16th centuries along the North Sea coast, roughly between the mouths of the Rhine and Weser rivers. The Frisian settlers on the coast of South Jutland (today's Northern Friesland) also spoke Old Frisian, but there are no known medieval texts from this area.

When conditions improved, Frisia received an influx of new settlers, mostly Angles and Saxons. These people would eventually be referred to as 'Frisians' (Old Frisian: Frīsa, Old English: Frīsan), though they were not necessarily descended from the ancient Frisii.

One major difference between Old Frisian and modern Frisian is that in the Old Frisian period (c. 1150 – c. 1550) grammatical cases still existed. Some of the texts that are preserved from this period are from the 12th or 13th, but most are from the 14th and 15th centuries.

Old Frisian was a language spoken between the 13th and 16th century, in the area between the Weser and the Zuiderzee. It is the common ancestor of the Frisian languages, Today, laws and deeds which use Old Frisian remain.

Old Frisian was a West Germanic language spoken between the 8th and 16th centuries along the North Sea coast, roughly between the mouths of the Rhine and Weser rivers. The Frisian settlers on the coast of South Jutland (today's Northern Friesland) also spoke Old Frisian, but there are no known medieval texts from this area.

Frisian, people of western Europe whose name survives in that of the mainland province of Friesland and in that of the Frisian Islands off the coast of the Netherlands but who once occupied a much more extensive area. In prehistoric times …

With this first etymological dictionary of Old Frisian based on the lexicon of Riustring 1 manuscript, Old Frisian becomes accessible to a wide circle of scholars of Germanic and Indo-European. The latest insights of Comparative Indo-European Linguistics have been systematically incorporated.